The present invention is directed to a step ladder stabiliser for ensuring a step ladder remains upright when in use, comprising a folding member ensemble which can be stored on the subject ladder and then folds down advantageously in an automated action when the step ladder is opened. The invention derives a central tubular support leg of two sections, with a foot, which extends from the step ladder side at its upper hand rail and two lower mounted supporting tubular struts which also extend from the step ladder but on both sides, to adjoin laterally with the lower section of the support leg at two points. Rotating and pivoting joints at the ends of the leg and struts enable the adjustment of the leg and its gripping foot and also enable the rapid folding away when not in use.